Bare C5R Racing Cubed Cylinder Head


  • Capable of over 800 HP
  • Designed for big bore (4.100″ min) LS7/C5R/LSX blocks
  • 210cc “as-cast” intake ports
  • 70cc “as-cast” exhaust ports, same as production LS6
  • 30cc “as-cast” combustion chambers


SKU: 25534393 Categories: ,

Bare C5R Racing Cubed Cylinder Head

P/N 25534393

  • 355-T7 “as-cast” Aluminum racing head
  • Professional porting and machining of combustion chambers required
  • No seats or guide machining
  • C5R rectangle-port design – requires aftermarket rectangle-port intake manifolds
  • Designed for big bore (4.100″ min) LS7/C5R/LSX blocks
  • 210cc “as-cast” intake ports
  • 70cc “as-cast” exhaust ports, same as production LS6
  • 30cc “as-cast” combustion chambers
  • All fasteners are metric
  • Capable of over 800 horsepower!
  • Standard LS exhaust port design

Note: Images represent a machined version of the P/N 25534393 cubed (unmachined) product. Chevrolet Performance does not supply a fully machined version of the C5R head. Images are for reference only.

Additional required components:

  • 12582179 (2) or 19170419 Gaskets
  • 11562524 (20) Bolts
  • 12558840 (10) Bolts
  • 12571164 Spark Plug

Engine application: C5R


Bare C5R CRacing Cubed Cylinder Head

25534393 Chevrolet Cylinder Head

Great cylinder-head airflow has been a key enabler of the LS-Series‘ exceptional performance. Chevrolet Performance delivers those power-building attributes to you with a range of production-style aluminum heads ヨ from the LS6 heads for smaller-displacement engines to LS7 style heads for 427-inch-and-larger combinations, our aluminum heads benefit from GM‘s extensive research and development program, ensuring maximum airflow without compromises. In fact, many professional builders use our heads as straight bolt-ons, with no further machining. Many of our assembled heads use premium machining and materials, including CNC finishing and porting, along with lightweight, hollow-stem valves, sodium-filled exhaust valves and ヨ on some heads ヨ lightweight titanium intake valves.

Aluminum LS Family Head Technical Notes:
ユ Manufactured from 319-T5 aluminum alloy
ユ High-efficiency combustion chambers
ユ Symmetrical intake and exhaust ports
ユ Angled spark plugs (14mm; 5/8″ hex; 3/4″ reach; taper-seat plugs)
ユ 15ᄚ valve angle (except C5R and LS7)
ユ Bolt-down-type rocker arms (except LSX-DR, LSX-CT)
ユ Center-bolt valve cover hold-downs
Fits Gen III and Gen IV Small-Blocks only

NOTE: Chevrolet Performance heads will not fit 4.8L and 5.3L engines, due to their smaller bore sizes.

Prop65WARNING: These auto parts can expose you to chemicals including phthalates and lead. Installing or using these parts can expose you to other parts containing these chemicals and to engine exhaust, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to